Have you tried Google Photos? It's working extremely well for me and I'm paying some nominal $9.99 to get 1tb of storage and which is more than adequate for my usage as it also replaces Dropbox (using Google Drive) and the tools for automatically backing up from my phone as well as my desktop work quite well.
I tried for a couple months two years ago when they launched it (the newest iteration with unlimited "small" photos etc.). I had some troubles keeping the sync going from the phone but that I know was mostly Apples fault not providing a decent background API for this task (it is now available so I assume google photos has begun using it). The showstopper for me has been the web application which was unable to power a medium size library with decent navigation / organization tools. One thing that Apple nails is that the "moments" feature is a very good replacement albums for lazy people, as pics are grouped by time/location automatically. Google showed me a single stream and a search bar, which is too little to go getting that picture set from the summer last year.
Also, the main view in Google photos had infinite scrolling which is an ok technology for streams (Facebook etc.) but very bad for people needing to jump back to specific points. Apple Photos navigation of moments with its three or four different zoom levels is far superior.
That said, I'm sure Google Photos has evolved in two years... I'd like to check back
